The long term goal of this project is to generate novel cytotoxic agents capable of inhibiting cancer cell proliferation based on the structure of the natural product epothilone. Epothilone inhibits cell proliferation via a mechanism similar to that of paclitaxel (taxolTM) but has superior properties. A library of epithilone analogs will be made by genetic engineering of the biosynthetic pathways for epothilone production. This approach should produce analogs which can not be made by synthetic chemistry approaches. Moreover, the amounts required for full-scale pharmaceutical application will more likely be produced by fermentation than chemical synthesis. In Phase I, the epothilone gene cluster will be cloned from the myxobacterium Sorangium cellulosum, characterized and validated. Preliminary attempts will be made to establish heterologous expression and production in a proprietary Streptomyces host/vector system. In Phase II, directed manipulation of the gene cluster to produce analogs will be done. The resulting library of analogs will be subjected to anti-cancer screens at the NCI. PROPOSED COMMERCIAL APPLICATIONS: There is an increasing need for novel anti-cancer drugs. The anti-cancer agent paclitaxel (taxolTM), which acts via a similar mechanism as epolthilone, generated a market of $813, 000, 000 in 1996. The compounds developed in this project should be of great commercial value for lead discovery as well as drug optimization.